INSTITUT FÜR WELTRAUMFORSCHUNG

IWF.OEAW.AC.AT

Technical Laser Ranging Workshop

Matera 2015

SP-DARTSingle-Photon Detection, Alignment and

Reference Tool

Georg Kirchner, Franz Koidl, Michael Steindorfer, Wang Peiyuan

INSTITUT FÜR WELTRAUMFORSCHUNG

IWF.OEAW.AC.AT

The basic configuration …

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� SP-DART is a small SLR station,but without receive telescope: It uses a host mount/ telescope

� Low energy laser transmitters:

- 532 nm / 2 kHz / 15 µJ / < 1 ns

- 1064 nm / 2 kHz / 30 µJ / < 1 ns

� FGPA for Range Gate etc.

� Event Timer, GNSS Receiver, MET

� Laptop, Real-Time programs

� Uses a host mount/telescope …

INSTITUT FÜR WELTRAUMFORSCHUNG

IWF.OEAW.AC.AT

Design Goal: Both beams at exit: 40 mm dia, minimum divergence (<25 µrad);

Both lasers operating parallel, no moving parts, pointing stability < 15 µrad

SP-DART: Dual Wavelength TransmitterThe laser transmitter

INSTITUT FÜR WELTRAUMFORSCHUNG

IWF.OEAW.AC.AT 4SP DART mounted on GRAZ telescope

Output Lens

2 µLasers:

532 nm

1064 nm

Dichroic

Laser bench, mounted on Graz telescope …

INSTITUT FÜR WELTRAUMFORSCHUNG

IWF.OEAW.AC.AT

SP-DART in Graz: Tracking Galileo 101

HQ-Laser / 532 nm:

350 µJ / 2 kHz / 10 ps:

25° El: 0.6 % Ret Quote

65° El: 8.3 % Ret Quote

DART-Laser / 532 nm:

15 µJ / 2 kHz / < 1 ns

56° El: < 0.1 % Ret Quote

63° El: 1.1% Ret Quote

- With 15 µJ: Ranging to HEOs possible; needs Single-Photon Sensitivity of Receiver

- Return Quotes are varying due to weather conditions / elevation etc.

- With several passes: Reasonable statistics obtained

INSTITUT FÜR WELTRAUMFORSCHUNG

IWF.OEAW.AC.AT

Details of tracking Galileo 101HQ-Laser: 350 µJ / 2 kHz / 10 ps / 532 nm:

@ 65° El: 8.3 % Return Quote

DART-Laser: 15 µJ / 2 kHz / 1 ns / 532 nm:

@ 63° El: 1.1% Return Quote

INSTITUT FÜR WELTRAUMFORSCHUNG

IWF.OEAW.AC.AT

SP-DART in Graz: Tracking Glonass 127HQ-Laser: 350 µJ / 2 kHz / 10 ps / 532 nm:

@ 73° El: 11.9 % Return Quote

DART-Laser: 15 µJ / 2 kHz / 1 ns / 532 nm:

@ 70° El: 3.2 % Return Quote

INSTITUT FÜR WELTRAUMFORSCHUNG

IWF.OEAW.AC.AT

SP-DART in Graz: Tracking LAGEOS-2

HQ-Laser / 532 nm:

350 µJ / 2 kHz / 10 ps

23° El: 10.3 % Ret Quote

DART-Laser / 532 nm:

15 µJ / 2 kHz / 1 ns

46° El: 1.3 % Ret Quote

55° El: 1.7 % Ret Quote

INSTITUT FÜR WELTRAUMFORSCHUNG

IWF.OEAW.AC.AT

SP-DART Transmitter mounted on Wettzell WLRS Telescope (30.Sept.2015)

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Graz supplied: 15 µJ laser => start pulses, ET, FPGA / Range Gate, Laptop + program;

Wettzell supplied: Mount / telescope / tracking; SPAD detector => stop pulses

Satellites tracked: ENVISAT, AJISAI, LAGEOS-2, Glonass-128, Galileo-102

SP-DART µJ laser mounted on Wettzell WLRS telescope

Graz SP-DART electronics

box with GPS T&F receiver, Riga USB-ET, FPGA, …

INSTITUT FÜR WELTRAUMFORSCHUNG

IWF.OEAW.AC.AT

SP-DART in Wettzell: Tracking Glonass 128;Return Rate: ≈ 3% (≈ 60 returns/sec with 15 µJ / pulse)

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INSTITUT FÜR WELTRAUMFORSCHUNG

IWF.OEAW.AC.AT

SP-DART in Wettzell: Tracking Galileo 102;Return Rate: ≈3% (≈ 60 returns/sec with 15 µJ / pulse)

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INSTITUT FÜR WELTRAUMFORSCHUNG

IWF.OEAW.AC.AT

SP-DART Applications …

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� SP-DART ranging in Graz: Establishes a reference:

� e.g. 1% to 3% return quote with 15 µJ from GNSS satellites

� Comparing this with other SLR stations: Allows independent test of receive channel

� Wettzell: Done at end of September 2015: About 3% return rates for HEOs

� Zimmerwald: Scheduled for mid of November 2015; anybody else interested ???

� Alignment & Setup Tests on standard astronomy telescopes / installing a SPAD:

� Testing such setups for later bi-static Debris Ranging:

� Villach / Astronomy telescope / 40 cm / 16”: Tests scheduled for 2016

� Kefallonia / Greece: 1.2 m telescope in 1400 m: Testing for bi-static ranging

� Adding a 15 µJ / ps / kHz laser head: => Pico-DART ☺

� To be mounted on any astronomy telescope;

� Results in a simple, small kHz SLR station, with ps accuracy up to GNSS ☺

� Upgrades: Adding Retro-Reflector + CCD for easy alignment parallel to host system

INSTITUT FÜR WELTRAUMFORSCHUNG

IWF.OEAW.AC.AT

We are slowly approaching our ultimate goal:

The small, handheld SLR station ☺

Thank you !

http://www.youtube.com/watch?v=5o6OtPJKRJ8

Video of Graz SLR station ranging to ILRS satellites